10.1.2 N-GET Service

The N-GET service is used by a DIMSE-service-user to retrieve Attribute values from a peer DIMSE-service-user. It is a confirmed service.

10.1.2.1 N-GET Parameters

Table 10.1-2 lists the parameters for this service.

Table 10.1-2 N-GET PARAMETERS

DIMSE Parameter Name Req/Ind Rsp/Conf
Message ID M
Message ID Being Responded To M
Requested SOP Class UID M
Requested SOP Instance UID M
Attribute Identifier List U
Affected SOP Class UID U
Affected SOP Instance UID U
Attribute List C
Status M

10.1.2.1.1 Message ID

This parameter identifies the operation. It is used to distinguish this operation from other notifications or operations that the DIMSE-service-provider may have in progress. No two identical values for the Message ID (0000,0110) shall be used for outstanding operations or notifications.

Note: The Message ID (0000,0110) is recommended to be unique within the scope of an Association, to support debug procedures.

10.1.2.1.2 Message ID being responded to

This parameter specifies the Message ID (0000,0110) of the operation request/indication to which this response/confirmation applies.

10.1.2.1.3 Requested SOP class UID

This parameter specifies the SOP Class for which Attribute Values are to be retrieved.

10.1.2.1.4 Requested SOP instance UID

This parameter specifies the SOP Instance for which Attribute Values are to be retrieved.

10.1.2.1.5 Attribute identifier list

This parameter contains a set of Attribute identifiers for which the Attribute Values are to be returned by the performing DIMSE-service-user. If this parameter is omitted, all Attribute identifiers are assumed. The definitions of the Attributes are found in the specification of the Information Object Definition in PS 3.3.

10.1.2.1.6 Affected SOP class UID

This parameter may be included in the response/confirmation. If included in the response/confirmation, this parameter shall be equal to the Requested SOP Class UID parameter value used in the request/indication.

10.1.2.1.7 Affected SOP instance UID

This parameter specifies the SOP Instance for which Attribute Values are returned. It may be included in any response/confirmation and when included shall be equal to the Requested SOP Instance UID (0000,1001) parameter value used in the invocation.

10.1.2.1.8 Attribute list

This parameter contains the set of Attribute identifiers and values which are returned by the performing DIMSE-service-user. It shall be included in the success response/confirmation.

10.1.2.1.9 Status

This parameter contains the error or success notification for the operation. It shall be included by the performing DIMSE-service-user in any response/confirmation. The following types of status may occur:

⎯ attribute list error: one or more Attribute Values were not read because the specified Attribute was not recognized. The Attribute Values that could be read are returned.

⎯ class-instance conflict: the specified SOP Instance is not a member of the specified SOP Class.

⎯ duplicate invocation: the Message ID (0000,0110) specified is allocated to another notification or operation.

⎯ invalid SOP Instance: the SOP Instance UID specified implied a violation of the UID construction rules.

⎯ mistyped argument: one of the parameters supplied has not been agreed for use on the Association between the DIMSE-service-users.

⎯ no such SOP class: the SOP Class was not recognized.

⎯ no such SOP Instance: the SOP Instance was not recognized.

⎯ processing failure: a general failure in processing the operation was encountered.

⎯ resource limitation: the operation was not performed due to resource limitation.

⎯ success: successful operation.

⎯ unrecognized operation: the operation is not one of those agreed between the DIMSE-service-users.

10.1.2.2 N-GET service procedures

The following N-GET procedures apply;

a) The invoking DIMSE-service-user requests the performing DIMSE-service-user to retrieve Attribute Value(s) by issuing an N-GET request primitive to the DIMSE-service-provider.

b) The DIMSE-service-provider issues an N-GET indication primitive to the performing DIMSE-service-user.

c) If the operation can be performed, then the performing DIMSE-service-user retrieves the requested Attribute Value(s) and generates a response indicating acceptance of the N-GET request primitive by issuing an N-GET response primitive to the DIMSE-service-provider. In this case the following procedure does not apply.

d) If the operation cannot be performed, then the performing DIMSE-service-user rejects the N-GET request by issuing an N-GET response primitive with the appropriate error code to the DIMSE-service-provider.

e) The DIMSE-service-provider issues an N-GET confirmation primitive to the invoking DIMSE-service-user, completing the N-GET operation.